Looking at the Alaskan VFR chart ( the only one I have ) the MSA from the East ( coming from ANC ) is 2.800 Ft. After passing the Chigmit Mountains the terrain is pretty flat until DLG, the highest obstacle in that peak at 2550ft near the IAF. ( Ironically a direct track ANC-DLG would keep you well clear of that Peak.)
Surely the guys had also a GPS moving map with terrain on it, and warnings probably. Must be something else...